1. Field of the Invention
The present invention relates to navigation of XML documents, and more specifically to a method for creating, using, and maintaining selective path signatures called hints, selected for materialization based on their usefulness value, to aid in the navigation of XML documents.
2. Description of the Related Art
Extensible markup language (XML) documents are often represented as document object model (DOM) structures or trees. Since XPath queries (see J. Clark and S. DeRose, “XML Path Language XPath”, 1999, found at http://www.w3.org/TR/xpath.) are evaluated by traversing these structures, a requirement of query optimization is to efficiently decrease the number of traversed nodes. The optimization task is more difficult when the query framework allows a syntax that enlarges the search space, such as wildcards and descendant queries.
To reduce the overhead of query processing, many database systems supporting XML rely on indexes. On one hand, due to space limitations, it is often not possible to maintain an exhaustive set of XML indexes. On the other hand, partial indexes are designed for access performance, and are not dynamic enough to restructure themselves in response to changing query workloads. A secondary data structure that uses very little storage space and tunes itself to address hot spots in processing can therefore be beneficial. Hotspots provide wireless local area network (LAN) service from a wide variety of public meeting areas, and they are an increasingly popular way to work and play on the go. There are currently thousands of hotspots worldwide, with new access points being added daily.